Nootropic agents (cognitive enhancers) constitute a promising group of medicines. Known nootropic agents include piracetam (N-carbamido-methyl-pyrrolidone-2), which was introduced into wide medical practice in the early 1980s. Other N-substituted-2-pyrrolidones (e.g. etiracetam, oxiracetam, aniracetam, pramiracetam, rolziracetam, etc.) have been synthesized.
U.S. Pat. No. 4,743,616 to Tanaka et al. describes N-acyl pyrrolidine compounds having endopeptidase inhibitory activity and which are reported to exhibit antiamnestic effects. Unlike the piracetam derivatives, the compounds described by Tanaka et al. contain a proline group.
Biologically active N-terminal pyroglutamic acid compounds having the formula: ##STR2## have been reported by T. Gudasheva and R. Ostrovskaya (Chem. Pharmac. J., 1985, N 11, pp. 1322-1329). Another reported (T. A. Gudasheva et al., Chem. Pharmac. J., 1988, N 3, pp. 271-275) biologically active compound is N-acylproline having the formula: ##STR3##
A substantial need exists for highly active and nontoxic nootropic agents which can be used for treatment of mental decline, caused by different damaging factors. The present invention is directed to addressing this need.